1. Field of the Invention
The present invention relates to a method for producing the catalyst and, more particularly, to iron-oxide based catalysts and a method for producing iron-oxide based catalysts for use in cracking, isomerization and transalkylation processes by reacting iron oxides doped with a lattice compatible metal with halogen compounds.
2. Background of the Invention
Many industrial processes involve acid-catalyzed reactions, such as cracking, hydrocracking, depolymerization, isomerization, alkylation, transalkylation, etc. The catalysts used in these processes are solids (e.g. zeolites, silica-alumina), liquids (ex. phosphoric acid, methane sulfonic acid, triflouromethane sulfonic acid, sludges of aluminum chloride, etc.) or gases (e.g. hydrofluoric acid).
Some metal chlorides or mixtures of metal chlorides have been used as acid catalysts. These metal chlorides include AlCl.sub.3, ZnCl.sub.2, FeCl.sub.3 or mixtures of metal chlorides such as AlCl.sub.3 -CuCl.sub.2 (in which CuCl.sub.2 acts as a promoter).
Several shortcomings exist with the use of these inorganic halides in industrial settings, including: 1. their inherent highly corrosive characteristics, 2. the need to control rigorously the water content of the sludge containing the catalyst, 3. the difficulty to disperse the catalyst in the reaction mixture, resulting in the need to use large amounts of catalyst and, 4. the environmental hazards associated with the recovery and/or disposal of the used catalyst.
For example, the typical acid catalysts of zinc chloride and ferric chloride contain 52 weight percent and 65.5 weight percent of chlorine, respectively.
A need exists to develop methods to synthesize new acid catalysts that do not have the shortcomings of typical metal chloride catalysts. The process should minimize the use of halogen material. Finally, the resulting product should provide for its easy reclamation from reaction mixtures and, be stable.